Leggio M G, Neri P, Graziano A, Mandolesi L, Molinari M, Petrosini L
Department of Psychology, University of Rome La Sapienza, Italy.
Exp Brain Res. 1999 Jul;127(1):1-11. doi: 10.1007/s002210050768.
Recently, we demonstrated the prevalent role of cerebellar networks in the acquisition of the procedural components of spatial information by testing hemicerebellectomized (HCbed) rats in a classical spatial task, the Morris water maze (MWM). As procedures used in the water maze are a mixture of different components (that is, general procedures, exploration procedures, direct reaching procedures), for optimally solving a spatial task all procedural components must be opportunely managed. Thus, severely impaired procedural learning of cerebellar origin can be better comprehended by fractionating the procedural facets. To this aim, a two-step water-maze paradigm was employed. Normal rats were first trained to search for a hidden platform moved to a different position in each trial, utilizing a water maze setting in which visual cues were abolished by heavy black curtains surrounding the tank. In this paradigm, normal animals solved the task by using general and exploration procedures, but they could not use direct reaching skills. A subgroup of these pretrained animals was then HCbed and, after recovery from cerebellar lesion, was tested in a water maze with normal environmental cues available, a paradigm in which normal animals develop abilities for reaching the target with very direct trajectories. Pretrained HCbed animals, however, did not display the typical spatial deficits of naive HCbed rats, persisted in exhibiting the scanning strategy learned during pretraining, and never displayed direct reaching skills. In conclusion, cerebellar networks appear to be involved in the acquisition of all procedural facets necessary for shifting behavior within the maze until direct reaching of the platform. The lack of flexibility in changing exploration strategies displayed by pretrained HCbed rats is interpreted by taking into account the well-known cerebellar frontal interplay sculpting a specific cerebellar role in the acquisition of spatial procedural steps.
最近，我们通过在经典空间任务——莫里斯水迷宫（MWM）中测试半侧小脑切除（HCbed）大鼠，证明了小脑网络在空间信息程序组件获取中的普遍作用。由于水迷宫中使用的程序是不同组件的混合（即一般程序、探索程序、直接到达程序），为了最佳地解决空间任务，所有程序组件都必须得到适当管理。因此，通过将程序方面进行细分，可以更好地理解小脑起源的严重受损的程序学习。为此，采用了两步水迷宫范式。首先训练正常大鼠在每个试验中寻找移动到不同位置的隐藏平台，使用一种水迷宫设置，其中围绕水箱的厚重黑色窗帘消除了视觉线索。在这个范式中，正常动物通过使用一般程序和探索程序解决了任务，但它们不能使用直接到达技能。然后对这些预训练动物的一个亚组进行HCbed处理，在从小脑损伤恢复后，在具有正常环境线索的水迷宫中进行测试，在这个范式中正常动物发展出以非常直接的轨迹到达目标的能力。然而，预训练的HCbed动物没有表现出幼稚HCbed大鼠典型的空间缺陷，坚持表现出在预训练期间学到的扫描策略，并且从未表现出直接到达技能。总之，小脑网络似乎参与了在迷宫中改变行为直到直接到达平台所需的所有程序方面的获取。考虑到众所周知的小脑与额叶的相互作用在空间程序步骤获取中塑造了特定的小脑作用，来解释预训练的HCbed大鼠在改变探索策略方面缺乏灵活性的现象。
